Mostrando postagens com marcador CustomView. Mostrar todas as postagens
Mostrando postagens com marcador CustomView. Mostrar todas as postagens

quinta-feira, 31 de julho de 2014

Android Sliding Menu using Navigation Drawer

You might have noticed that lot of android applications introduced a sliding panel menu to navigate between major modules of the application. Previously this kind of UI was done using some third party libraries where a list view and some swiping gestures used to achieve this. But now android itself officially introduced sliding panel menu by introducing a newer concept called Navigation Drawer.
Most of the time Sliding Menu (Navigation Drawer) will be hidden and can be shown by swiping the screen from left edge to right or tapping the app icon on the action bar.
In this tutorial we are going to learn how to use navigation drawer to add a sliding menu to your application.




Example Applications

You can see lot of popular applications like Facebook, Youtube, Google + already introduced navigation drawer menu in their applications. Following are the navigation drawer menus of multiple apps.
android navigation drawer facebook, google plus, youtube
In order to demonstrate navigation drawer, I am taking an example of Google+ navigation drawer and explained the process to achieve the same. But before starting the project I have downloaded required icons and using photoshop I have made each icon into different dimensions for xxhdpi (144×144 px), xhdpi (96×96 px), hdpi (72×72 px) and mdpi (48×48 px) drawbles.
Also I have downloaded navigation drawer toggle icon and included in drawable folders. You can get all the images in the source code of this tutorial. We need another image to replace the action bar up icon to toggle navigation drawer. Save following images and later add them to your project.

ic_drawer.png
ic_drawer ic_drawer ic_drawer


Let’s start by creating a new project..

Starting new Project

1. Create a new project in Eclipse from File ⇒ New ⇒ Android Application Project. I had left my main activity name as MainActivity.java and gave the package name as info.androidhive.slidingmenu.
2. I prepared required string variables for List View items and icon names in strings.xml. Open your strings.xml located under res ⇒ values and add the following code.






3. Android introduced a newer UI element called DrawerLayout for Navigation Drawer. Open your layout file (activity_main.xml) for main activity and type the following code.
Here FrameLayout is used to replace the main content using Fragments and it should be always the first child of the layout for z-index purpose.





Creating Custom List View Adapter

Creating a listview with a icon, title and a counter isn’t straight forward. We have to build a custom listview to achieve this. For this I am going to create a custom adpater class for listview which provides a custom layout for individual list item in the listview.
Before start coding the custom adapter, I am going to create required layout files for the list view.
We need the layout drawables to state the list item state when normal and pressed. It needs overall three xml files. One is for normal state, second is for pressed state and third one to combine both the layouts.
4. So create a xml file under res ⇒ drawable folder named list_item_bg_normal.xml and paste the following code. (If you don’t see drawable folder, create a new folder and name it as drawable)





5. Create another xml layout under res ⇒ drawable named list_item_bg_pressed.xml with following content.






6. Create another xml file to combine both the drawable states under res ⇒ drawable named list_selector.xml






7. We need one more drawable xml for rounde corner background for the counter value. So create a xml file named counter_bg.xml under res ⇒ drawable.
If you want to know how to add a rounded corner border layout, you can learn from How to add Rounded Corner borders to Android Layout





8. As listview has the custom layout, we need another layout file which defines the each list row. So create a layout file under res ⇒ layout named drawer_list_item.xml. This is a relative layout which places the icon, title and counter relative to one another.






As each list item contains three elements icon, title and a counter, I would like create a model to represent each list row.
9. I prefer to create a new package to keep all the model classes. So create a new package named info.androidhive.slidingmenu.model
10. Under model package create a new class named NavDrawerItem.java and paste the following code. Here isCounterVisible defines the visibility of the counter value. If you don’t want to show a counter for a particular list item you can set this to false.






11. Also create another package to keep all the adapter classes. Create a package named info.androidhive.slidingmenu.adapter.
12. Now we have all the files required for custom list adapter. So create a class named NavDrawerListAdapter.java under adapter package.







Until now we are done creating all the required layouts, model and adapter class for navigation drawer. It’s time to move on to our MainActivity.java and start implementing the navigation drawer.
Following are the major steps we need take care of in the main activity.
> Creating a NavDrawerListAdapter instance and adding list items.
> Assigning the adapter to Navigation Drawer ListView
> Creating click event listener for list items
> Creating and displaying fragment activities on selecting list item.
13. So open your MainActivity.java and add the following code. In the following code, we declared required variables, loaded the list items titles and icons from strings.xml, created an adapter and added each list item. Finally we added a navigation drawer listener.
invalidateOptionsMenu() is called in onDrawerOpened() and onDrawerClosed() to hide and show the action bar icons on navigation drawer opened and closed.







Now if you run your project you can see the navigation drawer with a listview. You can open the navigation drawer either clicking on action bar app icon or swiping the screen left edge to right. But you can notice that the click event for list item not working as it is not enabled yet.

Creating Fragment Views for individual List Item

You can see we have Home, Find People, Photos, Communities, Pages and What’s Hot in the list view. Here each list item represents a view where each view needs a Fragment class and a xml layout file.
14. So create a class file named HomeFragment.java and a layout file named fragment_home.xml with following content. For demo purpose I have created very simple layout for this view. You can customize this view depending on your app design.











Also you need to create remaining fragment classes and layout files for other list items.

Handling Navigation Drawer List Item Click Event

When user selects a list item from navigation drawer, we need to display respected view in the main view. This can be done by adding a list item click listener and loading respected fragment view in the call back event.
15. Open the MainActivity.java and add the following code. Here we added a click listener and loaded the related fragment view.







Now run the project and test the listview click event. You can see respected fragment is loading on selecting the list item. Following is the screenshot of my slider menu.
android navigation drawer sliding menu

Final Code

MainActivity.java












terça-feira, 22 de julho de 2014

Creating Custom and Compound Views in Android Tutorial




This tutorial describes how to create custom Views in Android. The examples explained below is developed in Eclipse 4.3, compiled in Java 1.6 and tested in Samsung Galaxy S3 Android 4.2. In this example we will create a custom view with two TextView. One to the left and other to the right as pairs. The custom styles can be configured from xml.
The Android provides various View classes for dealing with user interfaces. View’s are responsible for representing data to user and allow interactivity. Below are few of the common View classes and Layout that is being supported in android.

 

1. Different Android Layouts

A layout defines the visual structure for a user interface. It defines the way View’s can be placed on an Activity. Layouts can be declared in two ways.
  1. Declare UI elements in XML. Android provides a straightforward XML vocabulary that corresponds to the View classes and sub classes, such as those for widgets and layouts.
  2. Instantiate layout elements at run time. Your application can create and manipulate View and ViewGroup objects programmatically.
Below are the ViewGroup classes that android supports
  • Linear Layout
  • Relative Layout
  • Table Layout
  • Grid View
  • Frame Layout
  • List View
Below are some of the most common used Android View classes
  • Button
  • Checkbox
  • EditText
  • ImageView
  • ProgressBar
  • RadioButton
  • SeekBar
  • Spinner (ComboBox)
  • ToggleButton
  • WebView
  • Dialog

 

2. Why Custom Views in Android ?

All the above View classes and ViewGroup classes are good enough to create an solid android app. However, sometimes your app may have unique needs that aren’t covered by the built-in views. Such cases you will end up creating an custom View in android. The below example shows you how to create your own views that are robust and reusable.

 

3. Creating your custom View class

Declaring a custom View is much similar to declaring any other class in Java. While designing an custom class keep the following things in mind
  1. It should provide some easy to use interface and should use the memory efficiently.
  2. A Custom View should conform to Android standards
  3. You can provide custom styleable attributes that can be configurable from Android XML layouts
  4. Your View class should be compatible with multiple Android platforms
All the default View classes that are available in android extends View. The same way your custom View can directly extend the View class or you may extend one of the default View controls such as TextView. Now, override the constructor that takes a Context and an AttributeSet object as parameters.



 

4. Define Custom Attributes

You can provide custom styleable attributes that can be configurable from Android XML layouts. These attributes will control its appearance and behavior of View. You can create a values/attr.xml file in your project. To enable this behavior in your custom view, you can define custom attributes for your view in a resource element in attr.xml file.


In the above xml file, LovelyView is the name of the style. and leftLabel, rightLabel, leftLabelStyle and rightLabelStyleare the style attributes defines.

Once you define the custom attributes, you can use them in layout XML files just like built-in attributes. The only difference is that your custom attributes belong to a different namespace. Instead of belonging to the http://schemas.android.com/apk/res/android namespace, they belong to http://schemas.android.com/apk/res/(your package name)

Here’s how to use the attributes defined for LovelyView



Notice that, In the above code snippet, we are using the fully qualified name of the custom view class. If your view class is an inner class, you must further qualify it with the name of the view’s outer class.

 

5. Apply Custom Attributes

In the above two steps, we have configured the View stylable attributes in the XML. When a view is created from an XML layout, all of the attributes in the XML tag are read from the resource bundle and passed into the view’s constructor as an AttributeSet. We can read the attributes by calling obtainStyledAttributes() method.




Below is the complete View class code


 

6. Download Complete Example

Here you can download complete eclipse project source code from GitHub.



7. Output

Custom and Compound Views in Android